Drilling directional and/or horizontal wells requires the use of a survey tool, referred to as a steering tool, to monitor the well bore path and monitor the orientation of the drilling assembly. One method of transmitting the survey information required to measure the orientation of the drill bit and the well bore path is by the use of an electrical connector connected between the steering tool and the well surface for conducting signals. Horizontal or high angle well bores, unlike conventional vertical well bores, are used to drill long well bore intervals in the target pay zone. As a result, many horizontal wells are drilled live (producing oil/gas) which requires the use of blowout control equipment at the well surface and around the outside of the drill string. This requires that the electrical conductor conducting signals from a steering tool to the well surface be inside the drill string. Such methods are disclosed in co-pending patent applications Ser. No. 07/710,621 filed Jun. 5, 1991 and patent application Ser. No. 07/665,877 filed Mar. 7, 1991.
However, the well producing formation may be under pressured, that is, having pore pressure below geostatic pressure. In these cases, the well is required to be drilled with a fluid that will not damage the well formation, such as an inert oil base mud system or an aerated mud system. Aerated drilling fluids are air/gas systems used to carry cuttings to the surface. However, aerated mud and air/gas drilling presents a unique operations problem as back flow up the drilling string must be prevented. That is, when releasing the drilling fluid and connecting a pipe joint into the drilling string, back flow could cause cuttings to be carried into the drill string and result in plugging. While a float or check valve may be conventionally used on the bottom end of the drill string, the entire drill string must be blown down and repressurized after adding each additional pipe joint into the drill string, all of which will effect the drilling time, expense and efficiency. Therefore, intermediate check valves would be desirable in the drill string at various levels. However, with the use of an electrical conductor through the inside of the drill string intermediate floats or check valves have not been used.
In order to provide a solution to the above problem, the present invention provides a connectable and releasable wet connect which telescopically connects and disconnects an electrical conductor in the drilling string as required. When connected, the wet connect electrically isolates the transmitted power and/or signal from electrical ground and the drilling fluid. This allows free electrical communication between the downhole steering tool and the surface support/monitoring equipment. In addition to electrically connecting the power and/or signal, the present wet connect includes a check valve to prevent undesired backflow of drilling fluid up the drill string which could occur during various times during the drilling operation, but allows the downward flow of drilling fluid. Backflow usually occurs as a result of the annuals having a higher pressure than the fluid in the drill string. While this is common during live or unbalanced drilling, this backflow is prevented by the present invention.